Sealed motor-compressor,especially for small refrigerating units



B. w. LARSEN 3,482,759 SEALED MOTOR-COMPRESSOR, ESPECIALLY FOR SMALLREFRIGERATING UNITS Filed Feb. 5. 1968' Dec. 9, 1969 2 e 17 [A 7 18 UUnited States Patent US. Cl. 230-206 6 Claims ABSTRACT OF THE DISCLOSUREThe invention relates to sealed motor-compressor units of the typehaving an open lubricating oil sump in the lower part of the housingfrom which oil is conveyed to various parts of the unit for lubricatingand cooling purposes. In this type of unit the oil drains freely fromthe various parts of the unit back to the sump without the use of guidedreturn paths such as channels and pipes.

In prior art units of this type the return of oil to the sump involvesthe direct dripping of the oil into the sump accompanied by relativelyloud and undesirable drip noises.

In the present invention the oil is also allowed to return freely to thesump without the use of channels or pipes but at one or more drainpoints where dripping would otherwise occur there is or are providedguide elements in the form of wires, threads, strings or bands, etc.,which hang vertically and function to allow oil to run silently downthese elements to the sump instead of dripping directly from the drainpoints to the sump.

This invention relates to a sealed motor-compressor, especially forsmall refrigerating units, with circulated lubricating oil part of whichlatter drains ofi the stator or the compressor.

In motor-compressors of this type, part of the oil collects onstationary components and drips off into the oil sump. The quantity ofthe dripping oil may be considerable, because the compressors operatewith a surplus of oil suflicient for the latter to be used not only as alubricant but also as a coolant.

Many special measures have been adopted, in modern motor compressors, inorder to lower the noise level. The present invention has for itsobject, still further to reduce the generation of noise.

According to the invention, this object is achieved in that, at pointsof the stator or the compressor at which oil drains off a guide elementis attached which guides the oil at least over part of its return pathtowards the sump.

In this way the dripping noise is eliminated which, given a substantialdropping height such as encountered, for example, in a motorcompressorwith vertical shaft and high-up compressor, can become a considerablenuisance, especialy if the dripping noise occurs at irregular intervals.

The guide element may extend from the dripping point to the oil sump orto a point closely adjacent thereto. The oil will then return to thesump with dripping or, at least, drip only from a negligible height.Alternatively, the guide element extends from the draining point to thewall of the housing. From there it can likewise return to the sumpwithout making a dripping noise.

In many cases it is useful to provide welldefined draining points. Inthe case of a motor-compressor with vertical shaft and high-upcompressor, for example, this may be done in that the draining point isan aperture in the wall of the motor-carrying element on the side facingthe stator. Obviously, it is also possible to provide every one of anumber of such draining points with a guide element.

Guide elements can be provided in the shape of very simple, inexpensivecomponents. For example, the guide element may be a metal wire or band.Also plastic threads or bands may be used. The material may be stifi,resilient or even soft.

An embodiment of the invention has been illustrated diagrammatically inthe accompanying drawing which shows a sealed motor-compressor for asmall refrigerat ing unit in part-sectional side-elevation.

In a housing consisting of two halves 1 and 2 is arranged amotor-compressor 3. It consists of a motor section 4 and a compressorsection 5, the two sections being connected by means of a motor-carryingelement 6. The motor-compressor is suspended by means of severalsupports 7 which are fixed on the motor-carrying element 6 andsupported, via spiral-wound coil springs 8, on a strap 9 inserted in thehousing. For claritys sake this support arrangement has only beenillustrated partially; moreover, further components such as connectionpipes for the coolant, connection nipples, etc., have likewise beenomitted.

The only components of the motor section 4 which have been shown hereare the stator 10 with its winding 11, and the lower end 12 of thehollow motor crankshaft which is driven by the rotor. The shaft end 12projects into the sump 13 and, in known manner, conveys oil to thelubricating points, due to its hollow-cone formation. Surplus oil isthrown off in the region of the upper shaft end 14, to be intercepted bythe housing, and returns to the sump along the wall of the latter.Further amounts of oil are discharged in the main bearing of the shaft,in the region of the motor-carrying element 6, in the crank bearing, andin an auxiliary bearing in the upper part 15 of the compressor section.Oil is also thrown OK at various protruding points of the motor shaft,for example at the crank pin and the balance weight. In the presentembodiment the cylinders and silencing chambers constitute a ring-shapedcomponent 16 at the inner wall surface of which the discharged oil isintercepted. The oil runs downand collects in the motor-carrying element6, above the stator 10.

In the face of the motor-carrying element '6 adjacent the stator, anorifice 18 is provided in the wall portion 17, and oil that hascollected can drain off through this orifice. A wire 19 has beenarranged in this orifice along which the oil can drain to a pointimmediately adjacent the sump. Alternatively, a plastic strip 20,indicated by dotted lines, is used which bears on the inner wall surfaceof the housing 2. Furthermore, a plastic thread 21 depends from thelower end of the stator and conducts oil draining off along the outerstator surface into sump. Obviously, a plurality of identical guideelements may be provided at different points of the circumference. Thesemeasures ensure that appreciable amounts of oil, which could producedripping noises, are conducted silently to the sump 13.

I claim:

1. A sealed motor-compressor unit comprising a housing, a motor and acompressor disposed in said housing, an open oil sump in the bottom ofsaid housing, means for distributing oil from said sump to variouspoints in the interior of said housing, and at least one generallyvertically hanging and flexible guide element attached at a strategicpoint in said housing to provide a gravity drain path externally of saidelement for the relatively silent return of oil to said sump.

2. A motor-compressor according to claim 1 said guide element extendsfrom a draining point to a point immediately in the vicinity of saidsump.

3. A motor-compressor according to claim 1 wherein said guide elementextends from a draining point to an internal Wall surface of saidhousing from which oil can return reltively silently to said sump.

4. A motor-compressor according to claim 1, a stator casing for saidmotor, an orifice in said stator casing for draining oil from the insideto the outside of said casing, said guide element being attached in thevicinity of said orifice to provide at least a portion of an oil returnpath from said orifice to said sump.

5. A motor-compressor according to claim 1 wherein said guide element isa metal Wire or strip.

6. A motor-compressor according to claim 1 wherein said guide element isa plastic thread or band.

References Cited UNITED STATES PATENTS ROBERT M. WALKER, PrimaryExaminer US. Cl. X.R.

